To study the remodeling of alveolar bone after retraction of the maxillary incisors assisting with micro-implant anchorage in adult patients with maxillary protrusion by CBCT.

Forty patients who were treated with extraction of the maxillary first premolars with microimplant anchorage meeting the inclusion criteria were selected. The CBCT data before and after treatment were collected, and the Dolphin Imaging 3D measurement software was used to measure and analyze the height and thickness of the alveolar bone of the 80 upper central incisors and the 80 lateral incisors.

After retraction of the incisors assisting with microimplant anchorage, the labial alveolar bone height of the maxillary central incisors decreased (0.11 ± 0.33) mm, and the lingual alveolar bone height of the maxillary central incisors decreased (0.85 ± 1.23) mm. The labial alveolar bone height of the maxillary lateral incisors decreased (0.18 ± 0.42) mm, and the lingual alveolar bone height of the maxillary lateral incisors decreased (1.13 ± 1.14) mm. The reduction in the lingual alveolar bone height was greater than that of the labial side, and the difference was statistically significant (P < 0.05). The labial alveolar bone thickness of the maxillary central incisors increased (the root cervix, the root media and the root apex), and the difference was statistically significant (P < 0.001). The labial alveolar bone thickness of the maxillary lateral incisors also increased (P < 0.05), while the lingual alveolar bone thickness and the total alveolar bone thickness of the maxillary central and lateral incisors decreased (P < 0.001).

In adults with maxillary protrusion, the microimplant was used to assist the reduction of the anterior teeth. The alveolar bone height of the maxillary incisors was reduced, and the palatal alveolar bone height decreased more than that of the labial side. The alveolar bone of the labrum was thickened, and the palatal alveolar bone thickness and the total alveolar bone thickness of the maxillary incisors were reduced after treatment.

To investigate the changes in oropharyngeal airway parameters and hyoid position in skeletal ClassⅡ adult female patients with different vertical skeletal types who were treated with maxillary anterior teeth retraction with maximum anchorage, and to provide a reference for orthodontic clinical diagnosis and treatment.

This study was reviewed and approved by the Medical Ethics Committee, and informed consent was obtained from patients. Sixty adult female patients with skeletal ClassⅡ were selected and divided into a skeletal ClassⅡ normodivergent group and a skeletal ClassⅡ hyperdivergent group based on the patients’mandibular plane angle. In both groups, the bilateral maxillary first premolars were extracted and the maxillary anterior teeth were retracted with maximum anchorage. Cone beam CT(CBCT) images were collected before and after treatment, and three-dimensional measurement software was used to analyze oropharyngeal airway-related parameters.

After retraction of the maxillary anterior teeth with maximum anchorage, the 10 parameters related to the oropharyngeal airway did not exhibit statistically significant differences in the normodivergent group (P＞0.05), but the perpendicular distance from the highest point of the hyoid bone to the vertical line passing through the sella (H-X) value decreased (P＜0.001). In the hyperdivergent group, the oropharyngeal area at the level of the epiglottis tip (OPA-E), anterior-posterior diameters of the oropharynx at the level of the epiglottis tip (E-AP), most constricted axial area of the oropharynx (OPA-MCA), and anterior-posterior diameters of MCA area of the oropharynx (MCA-AP) decreased after treatment (P＜0.001). In addition, the oropharyngeal volume (OPV) decreased after treatment (P＜0.05), and the perpendicular distance from the highest point of the hyoid bone to the horizontal line passing through the sella (H-Y) and the highest point of the hyoid bone to the epiglottis base (H-Eb) values increased after treatment (P＜0.05).

After retraction of the maxillary anterior teeth with maximum anchorage, there is no change in the oropharyngeal airway in skeletal ClassⅡ normodivergent female adult patients, while skeletal ClassⅡ hyperdivergent female adult patients have a risk of reduction in the oropharyngeal airway after maximuim anchorage retraction of the maxillary anterior teeth.